1. Field of the Invention
This invention relates to a magnetic tape cassette and more specifically to a video tape cassette.
2. Description of the Prior Art
Magnetic tape cassettes, especially video tape cassettes, are lidded at the front opening where the tape inside is to be exposed, so as to protect the tape during storage and transportation from dirt and dust deposition which can lead to dropouts or general deterioration of the tape. Meanwhile, the modern trend in the art is toward miniaturization of tape cassettes, and attempts are being made to employ video cassettes using 8-mm-wide magnetic tapes and as small as or even smaller than the compact cassettes for audio recording, or so-called 8 mm video tape cartridges for use on small video tape recorders. Such smaller tape cassettes naturally involve difficulties in manufacture and assembly and require effective utilization of the reduced space within the cassette housing. On these grounds mere miniaturization of the existing video cassettes, whether of the VHS or Beta system, would not give satisfactory products and total redesigning would become necessary.
Generally, a lidded magnetic tape cassette comprises, as shown in FIGS. 1 and 2, an upper housing section 1 and a lower housing section 2 constituting a housing, and a lid 3 provided at the front of the housing, with pivots 5 on the inner surfaces of the both sides 4, 4' of the lid fitted in corresponding bearing holes of the housing section 1 or 2. The lid 3 is normally locked but, as the cassette is loaded into a tape recorder, it is automatically unlocked and pivotally swung open. As illustrated in FIG. 2, the conventional locking mechanism comprises a lock member 7 pivotally connected, by a pin 6, to a pivot hole formed in the mating peripheries on one side of the upper and lower housing section 1, 2, and a leaf spring 9 gripped between the two housing sections to depress one end 8 of the lock member. A hook 10 formed on the other end of the lock member 7 is adapted to engage with an inward projection 11 on a side 4 of the lid. Unlocking is accomplished by forcing a protuberance 12 of the lock member in the direction of the arrow A, against the urging of the leaf spring 9, and thereby turning the lock member 7 counterclockwise.
In the existing locking mechanism of the construction described, the lock member 7 and the leaf spring 9 are held by the upper and lower housing sections 1, 2. Therefore, they must be set together in the upper and lower housing sections, rendering the assembly a rather difficult operation with frequent failure and necessity of reassembling.